Facial horns
Baby dragon features are smooth and soft, but as a dragon matures he or she starts to form facial horns and head horns, the mane hair grows which is more fur like in texture; claws and talons harden and lengthen. Wings expand and the muscles form with exercise allowing the first glides. Puberty for dragons is dramatic physically as well as emotionally. Imagine having an adolescent dragon full of attitude in your house.
That sounds like a fiasco! It is wild enough with human adolescents.